Postural Orthostatic Tachycardia Syndrome
(POTS), the Chronic Fatigue Syndrome (CFS)
and Post-Inflammatory Fatigue
Symptoms
include lightheadedness or
dizziness (in all patients) associated with pallor, exercise intolerance and
fatigue in most, blurred vision, chest discomfort, shortness of breath or
hyperpnea, palpitations, tremulousness, clamminess, anxiety, nausea/abdominal
pain while standing, acrocyanosis, weakness (which must be related to a loss of
postural tone), headache (which must be provoked by orthostasis), flushing,
neurocognitive defects and sleep impairment. Associated findings are mitral
valve prolapse, and gastrointestinal illness including irritable bowel disease. A subgroup of mitral valve
prolapse patients are known to have autonomic dysfunction including a
hyperadrenergic state while abnormal serotoninergic pathways are one source of
neuro-intestinal dysfunction in irritable bowel disease.The relationship of
symptoms to orthostasis is a key aspect of orthostatic intolerance although some
patients may experience symptoms during sitting as well as while standing.
Therefore history taking is critical. Usually a long-standing history of
symptoms (on the order of 3 or more for 3-6 months) is necessary before the
diagnosis of chronic orthostatic intolerance should be confirmed.

Chronic orthostatic intolerance occurs with chronic failure of the autonomic
nervous system as in primary autonomic failure, multiple system atrophy, and
secondary autonomic failure in diabetes and Parkinsonism, but, with the
exception of familial dysautonomia, these are rare events in
children.

However, evidence for extensive involvement
of orthostatic intolerance diagnosed by HUT has recently been described
in a syndrome of postural tachycardia (POTS) characterized by symptoms of orthostatic
intolerance in association with a rapid heart rate when upright. Some patients
have severe hypotension. Patients run the gamut from minimally affected
to seriously disabled. Adolescents with the Chronic Fatigue Syndrome (CFS)
almost all have a variant of POTS which has also been noted in attenuated
form during post-inflammatory illnesses such as the post-Lyme syndrome
endemic to our area. Our preliminary data in adolescents and the work of
others have shown a form of orthostatic intolerance with uniquely abnormal
neurovascular physiology related to other forms of orthostatic intolerance.
Indeed, the only effective treatment for CFS in adults and children
seems to target orthostatic intolerance. The cardiovascular form taken
by OI in these syndromes is distinct in producing low blood pressure without
overt fainting but with severe, often disabling postural symptoms associated
with tachycardia. Data suggest a post-inflammatory mechanism involving
abnormality in venous blood flow returning to the heart and resulting in
a hypovolemic state (low blood volume) not unlike hemorrhage.

We
found evidence for defective vasoconstriction and vascular pooling in these patients, in which purplish
discoloration and swelling of the legs occur (see figure). This is particularly obvious
in those with the worst clinical symptoms. Although these problems are
described in adults, little is known concerning its diagnosis and treatment
in children, particularly in teenagers.